HL2 Ep2 Graphics problem

[beats]

Gday. I'm playing through Episode two and up to the stage where you've just broken the car and need to destroy the autogun. I jumped on top of a building and all of a sudden the whole screen went black except for a block of blue where the sky should be. I can still move my mouse around and interact with the menu, even though I cant see it. I started playing Lost Coast and got a little way through and the same thing occurred.

I'm running a core 2 duo T7250 @ 2GHz, a GeForce 8600 GTM, and 4GB RAM.

If anyone has any ideas please let me know, I wanna finish the game dammit!
Cheers,
Beats

 

[leib10]

Verify cache integrity and try again. If problem still occurs, reinstall it.